The Cost of Immortality
by EdithFinch
Summary: The Doctor takes Clara on what should be a "normal" adventure, to see the Lights of Nesperion. But things go wrong, possibly worse than anything Clara could have imagined. The Doctor's dark side comes out, and he makes a mistake so big, it leaves Clara seriously questioning his sanity. Wee bit of past companions. First (published) fanfic, please R&R. One-shot.
1. Chapter 1

**Disclaimer: I do not own Doctor Who or any of it's characters... yet. :)  
****However, this work is copyrighted and use of it is permitted only with written consent from the author.**

**Gosh I'm so blunt. Sorry. Anyways, enjoy!**

Clara spun around and ran down the metal hallway. Lights were flashing red and alarms were blaring. The Doctor had taken her to see the famous light show over the planet Nesperion, and, needless to say, things had not gone well. The natives had blamed the Doctor for angering their God, claiming that the Last Great Time War had caused their God to send the whole planet into starvation. As punishment, they took Clara prisoner, and convinced the Doctor that they were torturing her, as they knew that his weakness was his companions. In reality, she was fine and had escaped, which brings us to her running down the hallway.

She came to a dead end, but luckily there was a door, and she yanked it open, completely unprepared for what she saw. The Doctor stood over one of the natives, bloody dagger in hand. He himself had rips in and blood splattered on his clothing, even his beloved bow tie was askew. But his eyes, oh, his eyes were filled with a rage Clara had never seen in him before. Mere seconds after she opened the door, he leaned down and stabbed the alien in the gut. Clara gasped, knowing she should run, but unable to move an inch. The Doctor turned towards her, a look of surprise on his face.

"Clara!" She didn't respond, she was speechless.

"Clara?" The Doctor's eyes softened.

"Doctor, where are we?" He looked at Clara confusedly, hadn't she just seen him take a life?

"On a Nesper spaceship, right above the planet."

Clara simply nodded, so the Doctor grabbed her hand and muttered, "Follow me." He led her to what looked like a small control room, with a window overlooking the small planet. He let go of Clara's hand and started fiddling with the controls. In shock, Clara simply looked at her hands, which were now also stained with blood. Snapping her gaze away, she slowly walked to the window, gazing upon the foreign world. Suddenly, she heard a loud smack, and turned to see the Doctor slamming down on a small purple button, which had been covered by a glass case. Her brows furrowed together and she heard a loud explosion outside the spaceship. She whipped her head around, only to see that there was no longer a planet outside, only bits of rock floating about.

"Doctor, what just happened?"

He didn't answer her, simply grabbed her by the wrist and jerked her towards the TARDIS. She struggled against his grip, trying to keep her eyes on what was left of Nesperion. It was no use, though. The Doctor was much stronger than her, and he shoved her into the TARDIS.

She fell to the floor, and he shut the door behind them. He then ran to the console and directed his ship to float in the vortex. Clara took her time getting up, and when she finished, she kept her eyes on the floor.

"So much blood… And pain, and there must have been time for suffering… And, and so much death…" She looked up at him, speechless at what he had done, and his eyes, which were filled with anger and hatred moments before, were now filled with a deep sadness.

"Why would you show me that?" She whispered. Then, suddenly, she snapped her gaze to the floor. "No… Thank you, for showing me that."

"Clara, I-" the Doctor tried to communicate.

"No, really, Doctor, thank you." She looked at him once more, quite menacingly. "I've always wanted to see the other side of you, the side you hid from me. Well, you know what they say: be careful what you wish for. 'Cause now I've seen that side of you, Doctor. And I'm _not_ quite sure I like it."

With that, she gave him a sad look and briskly walked out of the console room. For a moment, he just stood where he was, debating whether to leave Clara alone or go after her. He decided on the latter.

The Doctor ran out of the console room, down the left hallway, past the three purple doors, past the pool, library, and kitchen, up the stairs, back down the stairs, turned right, and finally came upon the orange door with the engraving of a large leaf on it. He rapped lightly on the door three times: there was no answer.

"Clara?" He tried turning the doorknob, but it was locked.

He reached into his pocket to retrieve his sonic screwdriver, but the TARDIS sent a small electrical shock through his feet.

"Ow!" The Doctor complained, "What was that for?"

To this, the TARDIS sent an angry hum through the hall. The Doctor placed his hand on the wall and slowly rubbed it, trying to soothe his beloved time machine.

"Hey… Sexy? Please let me see her?"

The ship was silent for a moment before making a buzzing sound, similar to television static. The Doctor turned his back to the wall to see Rose and Amy standing in front of him, frowning. The image of Rose spoke first, "You hurt her, Doctor."

"Rose-"

"Just listen to us, Raggedy Man," Amy cut in, and the Doctor hung his head. "She knows you caused it."

His head snapped up at this. "It's a fixed point in time!"

"Don't give us that crap, Doctor." The redhead snapped.

"The Night of Nesperion may be a fixed point, but _she _didn't have to be there to witness you commit _genocide._ The same crime you punished your human duplicate for!" Rose's eyes were filled with a sad sort of anger, and the Doctor knew he was not winning this argument. He slid down the wall until he was sitting. He looked at his bloodstained hands, and tears began to form in his eyes. He tried to hold them, but they raced down his cheeks.

"I have lost so many people. I lost you two-"

"You didn't lose us, silly!" Amy said, smiling kindly. Rose crouched down so she was eye level with the broken Time Lord.

"We will always be with you, Doctor. You've changed our lives for the better." Amy nodded at this in agreement, and Rose continued. "And while we wish we were still with you, we aren't. We can't take care of you, Doctor. So you need Clara."

"Go get your soufflé girl, Doctor!" Amy chimed in.

The Doctor was silent for a moment, and when he looked up, his past companions were gone. He laid his head back against the cool metal of the TARDIS's wall. After a moment, he heard Clara.

But she wasn't talking. She was weeping.

He listened as she sobbed- presumably into a pillow -and he wasn't there to comfort her. Because he was the one who made her cry. When this realization hit him- that he had probably scarred his impossible girl for life, he dissolved into tears again, too.

And that night, there was no light bickering, no talk of what adventure was planned for tomorrow. That night, the TARDIS was silent. The only sound was of the passengers shedding bitter tears.

For that is the true cost of immortality: sadness.


	2. Author's Note

**Author's Note:**

Hello, thanks for reading! Due to multiple requests (and ideas I am unable to remove from my mind) I will be continuing this with a longer sequel, if you're interested. I haven't published it yet, but keep an eye out for it. :)

Until then, please do check out my other stories! For _Sherlock,_ I have 'Toying With Me,' and I have a new_ Doctor Who_ and_ Downton Abbey_ crossover, with one of my OC's, Anna Reynolds. It's called 'The Taste of Time,' and it's very different from most DW/DA crossovers I've seen, and I'd love it if you would check it out!

-Edith XOXO


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